Oil burner

ABSTRACT

A GUN TYPE OIL BURNER PROVIDED WITH A BAFFLE PLATE BETWEEN THE BLOWER AND AIR INLET, COMBINED WITH SOUND DEADENING MATERIAL SO ARRANGED AS TO MATERIALLY LESSEN THE FAN NOISE.

June 6, 1972 N. E. FLOURNOY 7,

011. BURNER Filed Dec. 7, 1970 2 Sheets-Sheet 1 FIG. l

June 6, 1972 N. E. FLOURNOY 3,

on. BURNER Filed Dec. 7, 1970 2 Sheets-Sheet 2 United States Patent3,667,894 OIL BURNER Norman E. Flournoy, Richmond, Va., assignor toTexaco Inc., New York, N.Y. Filed Dec. 7, 1970, Ser. No. 95,651 Int. Cl.F23d 11/00 US. Cl. 431-114 4 Claims ABSTRACT OF THE DISCLOSURE A guntype oil burner provided with a bafile plate between the blower and airinlet, combined with sound deadening material so arranged as tomaterially lessen the fan noise.

The present invention relates to a gun-type oil burner and particularlyto the suppression of fan noise in a burner employing a rotary orsquirrel cage type pump or fan.

In the conventional gun-type, household oil burner, for example, thenoise of operation has always been a matter of concern although therelatively low pressures conventionally employed can permit use ofrelatively low power drive motors of relatively low rotational drivespeed.

Where, however, the speed and power of the motor is increased, thepropensity toward operating noise likewise can become objectionable.This is particularly true in the case of gun type burners which operateat relatively high plenum pressures as referred to, for example, incopending applications, Ser. Nos. 78,069, 739,469, now Pat. No.3,549,122, and Ser. No. 104,043. It has been found desirable, in suchequipment, to operate with a barrier plate in the blast tube, providedwith orifices such that a substantial pressure upstream of the barrierplate is employed to support high velocity and high kinetic jets orstreams of air thru the orifices and in the vicinity of the burner tip.

This means, of course, that the rotary pump or sqirrel cage fan mustnecessarily operate to maintain a substantially higher pressure but withno greater actual flow rate than the conventional burner for which it isa substitute. This accordingly means additional air slippage or what issometimes euphemistically known as stalling of the rotary squirrel cagetype of pump which may be likened to a form of free wheeling in whichthe blower rotates at higher speed to maintain pressure but withoutproducing corresponding flow. Under these conditions the blade tips passat high speed thru a gas under pressure which is not flowing as it wouldif the pressure were lower. This produces a blade tip effect involving aturbulence such that the noise-making tendency is substantiallyincerased.

It is therefore a purpose of the present invention to obviate theforegoing difiiculty by, in large measure, effecting a diversion anddeadening of the sound waves in a simple and effective manner. This isaccomplished by a restrictive barrier which cuts ofi. a portion of theinlet chamber from communication with the air pump, diverting the soundwaves from the fan blades to the opposite half of the chamber andspecifically toward the inner wall thereof. This half is, in turn,provided peripherally with a sound absorptive material which absorbs theimpinging sound waves such that the ultimate release of sound isunobjectionable.

One preferred, illustrative form of the present invention is shown byway of example in the present drawing wherein FIG. 1 is an elevationalview of an oil burner embodying the present invention as viewed from thetip end of the blast tube; FIG. 2 is a side elevation taken on the line22 of FIG. 1, with the air inlet chamber shown in vertical section; FIG.3 is a smiilar sectional plan view of the burner taken on the line 33 ofFIG. 2.

Referring now to the present embodiment, the burner comprises aconventional blast tube 10 provided with a frusto conical tip 12 and aplenum chamber 14. A squirrel cage type fan shown in FIG. 3, as at 16,is located in the plenum chamber 14 and driven by motor 18 via shaft 17.Liquid fuel oil passes to an atomizing spray nozzle, not shown, in thetip of the blast tube via oil pump 20 and conduit 22. The electricalcontrols are housed in container 24.

The present invention is concerned primarily with controlling the noiseoriginating in the rotary pump, namely the squirrel cage blower 16.This, as is more specifically shown in FIGS. 2 and 3, comprises acylindrical, open sided wheel having a series of peripherally arrangedvanes 26, all extending axially and being formed in essentially the samecircumferential and radial directions to direct air outwardly into theplenum chamber as the wheel is rotated. The squirrel cage wheel alsocomprises radial spokes or spiders 28 and hub 30 which, in turn, isdriven by shaft 17 from motor 18 as aforesaid. Also, in the conventionalmanner a cylindrical air inlet chamber 34 is mounted on the side of theplenum chamber coaxial with the squirrel cage rotary fan 16 and open onits adjacent side so as to communicate with the interior of the squirrelcage.

The outer cylindrical surface of the inlet air chamber 34 is likewiseapertured or opened and provided with an air band 36 which is similarlyapertured or provided with a number of slots 38 so that by rotating theband 36 with respect to the cylindrical surface of the air chamber 34,the effective opening of the apertures and thus the air inlet may bevaried at will. The band 36 is, in turn, tightened or loosened on theinner chamber by means of fastener 40.

Referring now more specifically to the details of the present invention,sound control is primarily effected by an intake air silencer comprisinga flat, semi-circular plate 42; see FIGS. 2 and 3.

Plate 42 is, as shown, provided with a circumferential, semi-circularmargin 44, such that it covers one-half of the axial opening 43 in theend of the inlet air chamher as shown in FIG. 1; moreover, beingsemi-circular in shape and recessed at 46 to accommodate the drivingshaft 17. The plate 42 is held in place by a lower laterally extendingflange or tab 48 attached to an abutting projection 49 on the chamber orhousing 34 by fastener 50. Preferably, as is shown, the plate 42 isformed out of relatively heavy material to avoid vibration and fitssnugly against the inner flange of housing 34 as shown in FIG. 1. Also,it may and preferably is formed of suitable sound-deadening material ofthe type represented by lead, tin or the like. On the other hand, whereeconomy dominates, a mild steel or preferably an aluminum plate will do.

In any event, the member 42 at least performs the function of sealingoif and diverting at least one-half of the sound which otherwise wouldemanate thru the circular passageway between the plenum and the inletair chamber. Furthermore, the diversion of the sound waves is in adirection indicated more or less diagrammatically by the arrows in FIG.3, namely toward the peripheral inner surface of the cylindrical inletchamber and specifically along the segment opposite the semi-circularplate 42.

In the interest of clarity it is to be particularly noted that thearrows as shown in FIG. 3 are not intended to represent flow of air orany other fluid which, in actual fact, flows in the opposite direction.On the contrary, these arrows specifically show and represent the pathof the sound waves in passing from the burner.

To absorb the nascent sound waves now impinging directly on the righthand half of the inner portion of the inlet chamber as viewed in FIGS. 2and 3, this surface is provided with a sound deadening materialrepresented as at 52 in FIGS. 2 and 3.

The class of sound deadening material has been broad- 1y treated in manyfields including some considerably remote from the present one. Sinceconsiderations which contribute to success in the absorption of soundare well known, these will not be extensively covered here other than tosay that such materials are usually composed of relatively softmaterials. Accordingly, the present invention contemplates the use ofsuch sheet materials in the position indicated by reference numeral 52.

A preferred material which has been found suitable for the presentpurpose is a corrugated asbestos board composed of relatively softasbestos fibres arranged in typical corrugated form with one fiat sheetsupporting a corrugated sheet such that the thickness approximates inthe neighborhood of A3" to ii The flat sheet of the board is providedwith a layer of aluminum foil and the corrugated interior sheet ofmaterial is readily amenable to curvature to precisely fit the interiorannular surface of the air inlet chamber and more specifically, thefiat, foil-covered surface can be bent to fit the interior surface ofthe air inlet chamber with the corrugated layer interiorly thereof andis preferably cemented thereon with Scotch Grip or some other commercialinsulating adhesive. Moreover, the radially internal corrugations, whilepermitting curvature of the corrugated board as previously indicated,tend by virtue of the curvature to be brought closer together which isbelieved to yet further involute the interior interstices and thus thesound absorptive and sound deadening qualities of the absorbent areimproved.

The general arrangement of the corrugated asbestos board 52 is indicatedin FIG. 2 wherein the corrugated portion of the board is shown insection on the interior surface thereof, with the parallel corrugationsand the radially interior face being shown more clearly in FIG. 3.

Also, as previously intimated, the layer of sound absorptive material 52covers circumferentially the entire cylindrical portion of the interiorsurface of the inlet chamber which is not cut off or overlaid by thesemicircular plate 42.

Therefore, as indicated in FIG. 3, the objectionable sound generated bythe high speed passage of the squirrel cage fan blades thru the highpressure area passes outwardly, as shown by arrows 56, meeting thebarrier plate 42 which diverts them to the right as shown in FIG. 3 intodirect impingement with the absorptive board 52. Such of the reflectionsas are not completely absorbed, shown by the dotted line arrows 58continue outwardly thru the openings in the housing 34 and thru theperipheral band 36.

Irrespective of the functional explanation of the effect and thequestion of to what extent sound is absorbed or diverted by indirection,the fact remains that the noise abatement is so apparent that it isquite apparent to any ordinary observer without resorting tocomprehensive technical noise measurements.

I claim:

1. In a gun type oil burner having a blast tube supplied with air underpressure from a plenum chamber by a squirrel cage type blower which issupplied with air from an annular, air-inlet chamber arranged coaxiallywith respect to said squirrel cage blower fan and having a circularlateral side opening opposite the side of such squirrel cage fan forsupplying air axially to the interior thereof, means for deadening theobjectionable sound produced by the operation of said fan comprising,

an essentially semi-circular plate covering approximately one-half ofthe opening between said air inlet chamber and said squirrel cage fan,thereby to divert sound produced by said fan into the semi-circularsection of said air inlet chamber opposite the uncovered half of saidopening and toward the inner periphery of said annular air inletchamber, and

a sound absorptive deadening layer of material occupying the annularinner surface of said air inlet chamber thruout the semi-cylindricalwall section thereof opposite the uncovered half of said opening wherebysaid diverted sound impinges said sound deadening layer before passingfrom said chamber.

2. A gun type oil burner as defined in claim 1 wherein said sounddeadening material comprises a layer of corrugated sound absorptivematerial.

3. A gun type oil burner as defined in claim 1 wherein said sounddeadening material comprises a layer of corrugated sound absorptivematerial comprising a flat layer of sound absorptive material cementedto the interior of said air inlet chamber,

and a corrugated layer of sound absorptive material fastened to saidfirst layer with the corrugations facin'g inwardly.

4. A gun type oil burner as defined in claim 3 wherein said sounddeadening material comprises relatively soft asbestos with thecorrugations on the interior surface thereof and extending axially ofsaid chamber.

EDWARD G. FAVORS, Primary Examiner

